for using the ActiveX component of the reader I need the CLSID. So far no problem, everything works like a charm with the Reader 8. But now I heard that every version of the Reader has its own CLSID. Is there any list of the CLSID of recent versions? Or is that just a rumor?

You should probably use the registered name rather than the CLSID,
which is indeed subject to change. There aren't many versions to worry
about though, the first supported Reader component came in with 7.0.
(There was an unsupported and undocumented component before).